docs: def vertices(self):
          """
          Returns the vertices of the halfspace intersection
          """
          if self._v_out is None:
              output = qhalf('Fp', self.halfspaces, self.interior_point)
              pts = []
              for l in output[2:]:
                  pt = []
                  for c in l.split():
                      c = float(c)
                      if c != 10.101 and c != -10.101:
                          pt.append(c)
                      else:
                          pt.append(np.inf)
                  pts.append(pt)
              self._v_out = np.array(pts)
          return self._v_out